Wi-Fi Technology

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Wi-Fi is a set of radio frequencies that eliminates cables, sharing an Internet connection and enables the exchange of data between several positions. The technology is known in the United States since 1997. There, there are 11 million access points against 80 in France. But France relaxed its laws on radio and is racing to turn on Wi-Fi: the major operators show their interest, compatible devices can be installed in radius. The transition to wireless networks opens new perspectives for community use of the computer. Cap on Wi-Fi!


Networks without son

Son a wireless network (wireless network in English) is, as its name suggests, a network in which at least two terminals can communicate without wired connection. Through networks without son, a user has the ability to stay connected while moving in a geographic area more or less extensive, this is the reason why we sometimes hear of "mobility".
NB: Note on spelling networks without son: Despite the use of "wireless" commonly accepted spellings are correct "no son" and "wireless" There is talk of "network without son" or "Wireless".

Networks without son are based on a connection using radio waves (radio and infrared) instead of the usual cables. There are several technologies are distinguished in part by the transmission frequency used and the throughput and transmission range. Networks without son can easily connect remote devices a dozen meters to several kilometers. In addition, the installation of such networks do not require heavy infrastructure facilities existing as is the case with wired networks. In consideration to the problem of the regulation relating to radio-electric transmissions. More radio waves are difficult to confine in a restricted geographic area, it is easy for an attacker to listen to the network if the information in clear text. It is therefore necessary to put in place the necessary arrangements so as to ensure confidentiality of data transmitted over networks without son.

Wireless Network: WiFi technology

1.1) The categories of networks without son
There are usually several types of networks without son, according to the geographical area with connectivity (called coverage):

a) Personal networks without son (WPAN)
Personal network without son (also called individual network without son or home network without son and noted WPAN Wireless Personal Area Network) networks without regard to the son of a small range: from a few tens meters. This type of network is generally used to connect peripherals (printer, mobile phone, home appliances, ...) or a personal digital assistant (PDA) to a computer without a wire connection or allow the connection between two machines without son little remote . There are several technologies used for WPAN: ? The main technology WPAN is Bluetooth technology, launched by Ericsson in 1994, offering a theoretical speed of 1 Mbps for maximum range of thirty meters. Bluetooth, also known as IEEE 802.15.1, has the advantage of being very energy efficient, which makes it particularly suitable for use in small devices. Version 1.2 including reduced interference with Wi-Fi networks ? HomeRF (Home Radio Frequency), launched in 1998 by the HomeRF Working Group (formed by manufacturers including Compaq, HP, Intel, Siemens, Motorola and Microsoft) offers a theoretical speed of 10 Mbps with a range of about 50 to 100 m without an amplifier. HomeRF standard bolstered by Intel, was discontinued in January 2003, especially since the founders of processors now rely on Wi-Fi technology embedded (via Centrino technology, shipping within the same component a microprocessor and a wireless adapter -Fi). ? ZigBee technology (also known as IEEE 802.15.4) provides wireless links at very low cost and with very low power consumption, which makes it particularly suitable to be integrated directly into small electronic devices (appliances, hifi, toys, ...). ? Finally infrared links allow you to create links without son a few meters with speeds up up a few megabits per second. This technology is widely used for home automation (remote) but suffers, however, disturbances due to light interference. The association IrDA (infrared data association) formed in 1995, has more than 150 members.

b) Wireless Local Area Networks son (WLAN)
The son WLAN (WLAN Wireless Local Area Network) is a network that covers the equivalent of a local area network or a range of about a hundred meters. It bridges between them-the terminals present in the coverage area. There are several competing technologies: ? WiFi (or IEEE 802.11), supported by the Alliance WECA (Wireless Ethernet Compatibility Alliance) offers speeds up to 54Mbps over a distance of several hundred meters. ? HiperLAN2 (HIgh Performance Radio LAN 2.0), European standard developed by ETSI (European Telecommunications Standards Institute), provides a theoretical speed of 54 Mbps on an area of ??a few hundred meters in the frequency range between 5150 and 5300 MHz. ? DECT (Digital Enhanced Cordless Telecommunication), standard domestic cordless telephones son. Alcatel Ascom developed for industrial environments, such as nuclear power plants, a solution based on this standard, which limits interference. Access points resist dust and water. They can monitor security systems 24/24h and connect directly to the telephone network to alert responsible for any problem.

c) metropolitan networks without son (WMAN)
Metropolitan network without son (WMAN for Wireless Metropolitan Area Network) is known as Local Loop (WLL). WMANs are based on the IEEE 802.16 standard. Wireless local loop provides a useful rate from January to October Mbit / s for a range of 4 to 10 kilometers, which this technology intended primarily for telecom operators.

d) extended networks without son (WWAN)
Son without the WAN (WWAN Wireless Wide Area Network) is also known as mobile cellular network. These networks without son since all the most popular mobile phones are connected to a WAN without son. The main technologies are: ? ? ? ? GSM (Global System for Mobile communication or Group Special Mobile) GPRS (General Packet Radio Service) UMTS (Universal Mobile Telecommunication System) Wimax (wireless network standard son pushed by Intel with Nokia Fujitsu and Prowim). Based on a frequency band of 2 to 11 GHz, with a maximum throughput of 70 Mbits / s over 50km range, some place it as a competitor to UMTS, even if it is more designed for mobile users.

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